in 2018, Facebook told Vox that it doesn’t use private messages for ad targeting. But a few months later, The New York Times, citing “hundreds of pages of Facebook documents,” reported that Facebook “gave Netflix and Spotify the ability to read Facebook users’ private messages.”
Surprising? No. Appalling? Yes.
Yes, although I think DMs are still visible to the instance administrator. I’m not sure if there’s a plan or what the timeline is for actually encrypting that information.